Intelligent fuse box for the power distribution system of a vehicle

ABSTRACT

The present invention relates to intelligent fuse box ( 1 ) for a vehicle&#39;s multiplex power distribution system, the fuse box including outputs ( 3 ) for driving the vehicle&#39;s functional components/actuators and/or cable buses ( 11–13 ) equipped with intelligent_nodes ( 14 ), the latter in turn having outputs for driving functional components/actuators ( 15 ), and further including means serving fuse functions between the outputs ( 3; 11–13 ) and the vehicle&#39;s power supply bus ( 12 ). The fuse-function means are controlled solid-state switches ( 4 ). The fuse box ( 1 ) includes inputs ( 5 ) for receiving messages controlling the ON/OFF state of solid-state switches ( 4 ) and a microprocessor ( 6 ), the latter controlling the solid-state switches ( 4 ) based on a program stored in the microprocessor memory ( 7 ) and on current limits predetermined in configuration data ( 8 ). In addition to the actual fuse functions, the controlled operation of the solid-state switches offer a plurality of auxiliary functions such as rush current limiting, programmable reconfiguration of current limits, dynamic fuse functions (e.g., to implement a low-current Asleep mode in a parked vehicle) and measurement of system overall load current.

The present invention relates to an intelligent fuse box for a vehicle'smultiplex power distribution system, whereby the fuse box includesoutputs for supplying the vehicle's functional components/actuatorsand/or cable buses equipped with intelligent nodes, that latter in turnhaving outputs for driving functional components/actuators, and furtherincludes means serving fuse functions between the outputs and thevehicle's power supply bus.

Known from patent publication EP 529,650 is a vehicle's multiplex powerdistribution system, wherein the outgoing buses from the supply powerdistribution point to intelligent nodes are individually protected byfuses that provide protection against both overcurrent and short-circuitsituations. These fuses are not implemented using solid-state switches.

Known from U.S. Pat. No 4,575,673 is a vehicle's multiplex powerdistribution system, whose intelligent nodes include electronic meansfor monitoring the load current and switching off the vehicle power tothe load if a given reference current level is exceeded with a duemargin in respect to inrush transients. Instead of being concentrated ina single fuse box of the system, the gated solid-state switches areincorporated in the control modules that are located in a distributedfashion. Hence, the system disclosed in U.S. Pat. No. 4,575,673 needs aseparate (conventional) fuse box between the vehicle power supply andthe bus outputs for protecting the buses and the intelligent nodeslocated along the buses.

It is an object of the present invention to provide an intelligent fusebox of the above-described kind that is suited for use as anintermediate unit between the primary power supply and a vehicle'smultiplex power distribution system.

Conventional fuse boxes are handicapped by plural problems such as:

-   -   due to their mechanical or thermal trip function, the fuse        elements cannot be adjusted for different overcurrent levels,    -   the fuse elements are of the slow-blow type, which inherently        invokes a fire hazard in a short-circuit or overload situation,    -   the trip levels of fuse elements are invariably nonprogrammable,        whereby it is impossible to meet the need for reducing the trip        level of a fuse element in an Asleep state, for instance,        without manipulating the mechanical fuse elements,    -   the fuse element cannot perform any interference filtration, and    -   last but not least, the life of mechanically tripping protective        elements is always limited.

These problems and limitations can be overcome by virtue of anintelligent fuse box according to the invention. Details of preferredembodiments of the invention are described herein.

In the following, the invention will be examined in greater detail withreference to the appended drawings, in which:

FIG. 1 illustrates an intelligent fuse box according to the invention ina block diagram.

DETAILED DESCRIPTION OF THE INVENTION

As illustrated, a fuse box 1 provides outputs 3 for driving functionalcomponents/actuators and/or buses 11, 12, 13 having coupled thereonintelligent nodes 14 that have outputs for driving functionalcomponents/actuators 15. Thus, the fuse box 1 may in a conventionalfashion have outputs 3 separately for each functional component/actuatorof the vehicle. Additionally, the fuse box may have coupled thereto oneor more buses 11–13 formed by current conductors complemented with dataconductors over which information is transmitted using some standardizeddata transmission protocol (CAN, LIN or IWS). Herein, CAN (ControllerArea Network) is a protocol conventionally used by automotive vehiclemanufacturers. IWS (Intelligent Wiring System) is a simplified versionof the CAN protocol adapted by the applicant. LIN is a master/slave-typeprotocol. As to the fuse box 1, the above-mentioned buses 11–13represent a single protected load, whose overcurrent trip level isdetermined by the summed nominal maximum current of the loads connectedto a given cable bus. The overload current monitoring of the loads 15coupled to the buses 11–13 is performed with the help of intelligentnodes 14.

The overcurrent trip functions are accomplished by means of solid-stateswitches 4 that are connected between vehicle's power supply 2 and theload outputs 3 or the bus outputs 11–13. In addition to conventionalovercurrent trip functions, the switches 4 can be employed to accomplisha number of other flexible functions to be described in more detaillater in the text.

The fuse box 1 also includes inputs 5 for receiving control messagessteering the ON/OFF state of solid-state switch 4. These controlmessages are submitted, e.g., from the control levers of turn indicatorsand windshield wipers, light switches and the like control switches ofthe dashboard, as well as from the sensors of functionalcomponents/actuators.

The invention is characterized in that a microprocessor 6 is employedfor controlling solid-state switches 4 on the basis of a memory-storedprogram utilizing the current limit values of configuration data 8. Theconfiguration data include the limits of a normal current window foreach one of outputs 3 or 11–13 and a trip limit that is substantiallyhigher than the upper limit of the normal current window. If the loadcurrent falls below the lower limit of the normal current window, afault alarm is issued to a display 9. Respectively, if the upper limitof the normal current window is exceeded, the current drive istemporarily cut off and, based on the configuration data 8, the programstored in memory 7 decides whether to continue or not driving the load.However, if the trip limit of output current is exceeded, the switch 4is invariably set into the OFF state in order to cut off the drivecurrent to the load.

The current monitoring functions for both the normal current window andthe trip limit are based on measuring the voltage over the solid-stateswitch 4 and/or the load, whereby the measurement value Is compared witha reference value of the respective memory-stored current limit in theconfiguration data. This comparison may be performed using, e.g., acontrol circuit described in international patent application WO00/69043 that serves a dual function in eliminating voltage and currenttransients occurring at either drive turn-on or turn-off. As generallyknown, turning on the load drive switches 4 involves a rush currenttransient that now can be eliminated by virtue of the intelligent fusebox according to the invention. More specifically, proper control of theswitch 4 makes it possible to inhibit a transient overcurrent peak or,alternatively, allow a short-duration overcurrent peak at acurrent-limited level without tripping the drive to the load at theinstant the solid-state switch 4 is controlled from the OFF state to theON state. As noted above, these current limits are predetermined withthe help of the configuration data 8. An additional benefit of theinvention is that the configuration data 8 are reprogrammable via aservice interface 10.

The facility of controlling the switches 4 in a programmable manneraccording to the stored configuration data can be further utilized toimplement dynamic fuse functions such that, e.g., permit givenfunctional components/actuators and/or cable buses to be driven at areduced current when the vehicle is parked stationary.

The measurement of the overall current load of the vehicle's multiplexpower distribution system can be arranged to take place based on, e.g.,the voltage drops over the switches inasmuch these signals are readilyobtainable from the overcurrent monitoring of the solid-state switches4.

The state, current and diagnostic data of the protective element servingas fuses can be stored in the system memory for later service needs and,respectively, the data can be transmitted to a display unit or remoteservice terminal. An optional bidirectional RF link between the vehicleand a service site is also feasible based on the information stored inthe intelligent fuse box.

In addition to the above-described benefits, the invention offers highersystem security and reliability, as well as longer life of the vehicle'selectronics and functional components/actuators by virtue of thesmoother control of load drive power. Moreover, the EMC interferencelevel is reduced.

The physical fuse box that houses the electronics circuitryaccomplishing the above-described functions may be designed to have asimilar size and dimensions as a conventional fuse box, whereby theadoption of the novel fuse box does not dictate a redesign of thevehicle's wiring system.

1. An intelligent fuse box (1) for a vehicle's multiplex powerdistribution system, comprising: a power source provided with vehicle'spower supply bus (2), the fuse box (1) being connected with the powersupply bus (2), at least one cable bus (11–13) between the fuse box (1)and vehicle's functional components/actuators, said at least one cablebus (11–13) being equipped with intelligent nodes (14) which in turnhave outputs for driving the functional components/actuators, each ofthe at least one cable bus (11–13) further having a power source endconnected to an output of the fuse box (1), the fuse box includingoutputs (3) for the vehicle's functional components/actuators andoutputs connected to the power source ends of the cable buses (11–13),and further including means serving fuse functions between the outputsof the fuse box and the vehicle's power supply bus (2), and said fusebox (1) further includes inputs (5) for receiving messages controllingthe ON/OFF state of solid-state switches (4), configuration data (8)including the limits of a normal current window for the outputs of thefuse box, and a microprocessor (6), the microprocessor (6) controllingthe solid-state switches (4) based on a program stored in themicroprocessor memory (7) and on the current limits predetermined in theconfiguration data (8), the configuration data (8) contributing underexternal control for altering the current limits, wherein theconfiguration data (8) are reprogrammable via a service interface (10)for altering the predetermined current limits.
 2. The fuse box of claim1, wherein the current-limiting function of the fusebox is madecontrollable based on comparing the voltage measured over saidsolid-state switch (4) and/or the load with a respective voltage valueof the configuration data which are stored in the memory (8) andcorresponds to the desired current limit.
 3. The fuse box of claim 1,wherein said solid-state switches (4) comprise a turn-on control that iscomplemented with a current-limiting function known as soft connectionthat is capable of inhibiting a transient overcurrent peak or,alternatively, allowing a short-duration overcurrent peak at acurrent-limited level without tripping the drive to the load at theinstant the solid-state switch (4) is controlled from the OFF state tothe ON state.
 4. The fuse box of claim 1, wherein said means servingfuse functions comprise controlled solid-state switches (4).
 5. The fusebox of claim 1, wherein the current limits include the limits of anormal current window with a lower limit and an upper limit wherebyviolation of the lower limit triggers a fault message while violation ofthe upper limit causes the load current drive to be temporarily cut offfor a time interval predetermined in the configuration data, and whereinin the configuration data is also stored a trip current limit which issubstantially higher than the upper limit of the normal current windowand at which the load current drive is permanently cut off.
 6. The fusebox of claim 1, wherein said solid-state switches (4) are controlled todrive given functional components/actuators and/or cable buses at areduced current when the vehicle is parked stationary.
 7. The fuse boxof claim 1, wherein the overall load current measurement of thevehicle's multiplex power distribution system is arranged to take placebased on voltage drops over the solid-state switches that are sensed tocontrol the switches in their fuse function.